This invention relates generally to containers housing a pressurized medium such as aerosol containers, self-chilling or self-heating food and beverage containers or the like and more specifically to an apparatus incorporated on such containers to automatically relieve pressure built up in the container upon such pressure reaching a predetermined level.
The aerosol valve art and the self-chilling and self-heating food and beverage container art is quite extensive. A major problem with regard to containers particularly in these arts which house a pressurized medium utilized in dispensing the contents of the container or to heat or chill the contents of the container is that the pressure of the medium can under certain circumstances reach a level, if not controlled, which will cause the container to rupture and possibly even explode thereby imparting injury to users. Various attempts have been made with such prior art containers to relieve the pressure prior to serious rupture of the container or the explosion of the container.
Some of the attempts which have been made to relieve such pressure include permitting the concave bottom of the can to expand outwardly thus increasing the volume in the can. An additional over pressure relief mechanism used particularly in aerosol cans includes having the necked in portion of the can stretch to increase the volume. This will cause the valve cup which carries the dispensing valve to also move. If the over pressurized condition within the container increases sufficiently it causes the valve cup to move by an amount sufficient to cause the periphery thereof to release from the edge of the container thereby allowing the over pressure condition of the pressurized medium to be relieved, i.e., a total failure. In some instances, there is provided coining a portion of the bottom of such container to weaken a section thereof in such a manner that when the pressure internally of the container reaches a predetermined level the material forming the container around the coined area releases and the contents of the pressurized medium exit the container thereby relieving the over pressure condition therein.
The known problem of potential over pressurization is recognized in the art to the degree that all aerosol cans prior to their transport in interstate commerce must be subjected to a hot water bath for a predetermined period of time for the purpose of determining whether or not the pressurized medium within the container expands to a degree to cause the known over pressurization relief mechanisms of the type above described to become activated. If such does not occur then the aerosol container is deemed acceptable for shipment and use. The step of subjecting such aerosol containers to the hot water bath is an expensive and time consuming additional step required in the production of such devices.
There is therefore a need for a simple and inexpensive over pressure release mechanism for utilization upon a container housing a pressurized medium, such as an aerosol can, which will automatically release the pressure upon the pressure reaching a predetermined level which level is well prior to a rupture or explosion of the can.
An overpressure release mechanism adapted for use on a container housing a pressurized medium, said container including a valve member having a valve stem for releasing the pressurized medium upon activation, said valve member carried by a pedestal which is movable relative to said container upon pressure in said container reaching a predetermined level, means defining a barrier disposed adjacent said valve stem and anchored to said container, said valve stem engaging said barrier upon said pedestal moving responsive to said pressure reaching said predetermined level and activating said valve to relieve said over pressure condition.
In accordance with a more specific aspect, the present invention includes an over pressure release mechanism adapted for use on a container housing a pressurized medium which includes a valve having a movable stem adapted for releasing the pressurized medium which valve is carried upon a mounting member affixed to and closing an open end of the container, the mounting member including a pedestal upon which the valve is mounted and which pedestal moves responsive to the medium exceeding a predetermined pressure internally of the container, a panel member carried by said mounting member and overlying said stem; said panel member being movable only toward said stem; said stem engaging said panel member upon said pedestal moving outwardly responsive to said medium exceeding said determined pressure and thereafter moving said stem to release the pressurized medium from the container thereby relieving the over pressure condition therein.